Scientists take another stab at nuclear fusion

LAWRENCE LIVERMORE LAB

Jim Doyle, Chronicle Staff Writer

Published 4:00 am, Wednesday, April 1, 2009

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After more than a decade of work and an investment of $3.5 billion, scientists at Lawrence Livermore National Laboratory say they have created a super laser that will enable them to build a miniature sun within the lab in the next two years.

The U.S. Department of Energy certified the world's largest laser on Tuesday, an instrument that will test the reliability of the nation's nuclear weapons stockpile, explore the origins of the universe and seek to create nuclear fusion energy.

By 2010 or 2011, the lab's scientists hope to achieve ignition - that is, produce the first tiny thermonuclear explosions inside their capsule targets in hopes of ultimately creating a limitless source of fusion energy, the kind of energy that powers the blazing heat of the sun and stars.

"It's an extremely exciting prospect," said Edward Moses, director of the laser project. "The search for fusion energy has been a long haul. Some people say it's better than you can believe, but based on everything we know, the question now is more 'when,' not 'if.' "

Researchers have dreamed for more than half a century of tapping the potential of nuclear fusion as a clean, cheap power source. If successful, nuclear fusion energy could be a game-changer for meeting the world's energy needs. Current nuclear power plants rely on nuclear fission, or the splitting of atoms, a chain reaction that produces large quantities of deadly radioactive waste.

But if this costly experiment at Lawrence Livermore fails, it could kill U.S. fusion research for good. Since the 1950s, scientists have tried different processes to create nuclear fusion but have failed. For all the money spent on research, fusion has yet to power a light bulb.

500 billion watts

The National Ignition Facility is 10 stories tall and three football fields in length, and its 40-foot-tall target chamber is shaped like a golf ball. Nearly 200 powerful laser beams are guided by a switchyard of mirrors to arrive at once at the target chamber. The goal is to ignite a tiny hydrogen fuel pellet and produce a burst of energy of up to 500 billion watts of power.

"This is the first time that we've built a laser that is capable of reaching the energy and power conditions that can drive the fusion process," Moses said. "We're going to be able to create temperatures inside these small targets of over 100 million degrees. That's hotter than the center of the sun, and very high pressures and densities are needed for fusion to occur."

Supporters say fusion holds no risk of a nuclear meltdown and will generate insignificant waste byproducts. But fusion's prospects have been greeted with skepticism.

Secretary of Energy Steven Chu, the nuclear physicist who previously headed the Lawrence Berkeley National Laboratory, joked to an audience at an energy conference at Stanford University in 2006 that "I'm going to skip (discussing) fusion because it will probably skip the 21st century."

The super laser project has been subject to repeated delays and cost overruns since the lab broke ground in 1997. It initially was budgeted at $1.2 billion and scheduled for completion in 2002.

Reliability experiments

Scientists also plan to use the giant laser to conduct experiments to gauge the reliability of the nation's aging nuclear weapons stockpile. The United States has not deployed any new nuclear weapons in more than 20 years nor conducted an underground nuclear test since 1992.

"Protecting the safety, security and reliability of our nuclear deterrent in a world without nuclear testing is one of the most important things we do," said Damien LaVera, a spokesman for the National Nuclear Safety Administration.

Additionally, scientists plan to use the Livermore laser to explore the origins of the universe, including the makeup of stars and planets within and outside our solar system. They will examine how materials behave at temperatures and pressures like those at the center of a star.

But perhaps the most critical use of the laser will be the search for nuclear fusion, lab officials said.

A nuclear fusion demonstration project could be up and running in 10 to 12 years, they say, bringing fusion energy a step closer toward commercialization.

"Now, the science can start in earnest," LaVera said. "The research really begins."